Well, in my day (the 60's and 70's) in the UK we just made passengers sign
an indemnity form absolving the club from any reponsibility for accident or
injury or loss. Known as 'blood chits', these seemed to satisfy whatever
rules were in force at the time, since the BGA must have been aware of the
practice - every club was doing it. I seem to recall that some instructions
eventually came down from on high about briefing passengers on how to use
their parachute, and what would happen if it was necessary to abandon the
glider. I used to give these instructions and then add " If I say jump,
don't say pardon?, because I won't be around for a discussion". I never flew
passengers at a club that did not own or rent their site exclusively, so
'operating a business' never arose. Needless to say I never had to jump, and
I don't think anyone else ever did either.

Alistair W